Traditional glazing for balconies or the like consists of a plurality of sashed glass panes mounted on upper and lower guide rails and adapted to slide laterally past one another. A major disadvantage with this type of glazing is that at most only 50% of the glazed-in area can be opened. Furthermore, the outer surfaces of the panes are awkward to clean.
Glazing structures have thus been proposed in which the panes can be stacked against a side wall of the balcony by pivoting about a vertical axis. In WO 89/05389 this is achieved by means of a double upper rail arrangement having a straight outer rail and an inner rail which curves inwardly towards the side wall of the balcony. Two slides are provided on the upper edge of each pane, one of which moves along the straight outer rail and the other along the inner rail. Within the curved portion of the inner rail the trailing edge of the pane turns inwards and the pane can be opened against the side wall of the balcony. Such an arrangement is however not particularly aesthetically pleasing and considerable friction can arise in the system.
In an effort to eliminate these drawbacks, WO 90/121183 proposes a structure in which the top edge pivot pin of the glass pane is fitted with a latch which immobilizes the pivot pin with respect to the upper rail when the pane is pivoted about the pivot pin. Since the leading edge of the pane is held stationary, no curved guide rail for the trailing edge is required. Whilst eliminating some of the disadvantages of the prior systems, the arrangement according to WO 90/121183 introduces its own drawbacks, one being that the pane must be tilted to disengage the upper trailing wheel from its guide rail before pivoting can commence. Since the leading edge of the pane is locked first only when pivoting has commenced, there is a risk that the trailing wheel may not disengage should the pane topple back before pivoting commences. The fact that the leading edge is locked only once rotation has commenced further implies that a flange protruding from the upper guide rail adjacent the opening for the trailing wheel is required to support the trailing wheel during the initial opening operation. Such protruding flanges hinder the possibility to mount curtains or blinds across the glazing. In addition, because only the upper leading pivot pin is immobilized, the pane cannot be opened through more than 90.degree. due to the fact that the lower leading pivot pin would otherwise be forced along the lower guide rail as a result of the change in position of the center of gravity of the pane.
One solution to the problems described above is the subject of Swedish patent application no. 9000287-4. Said application discloses a pivotable, sliding, glazing structure comprising one or more panes supported between upper and lower guide-rails for horizontal sliding movement therealong, each pane having a leading edge and a trailing edge and being adapted to perform a pivoting motion about its leading edge at a predetermined position along said guide-rails by means of a pivot arrangement carried on said pane and arranged in the vicinity of the leading edge, said structure further comprising means for locking the pivot arrangement at said predetermined position before and during said pivoting motion.
Whilst the above structure offers certain benefits over prior arrangements, actuation of the locking means is relatively complicated.